A packaging apparatus can be used to package a food product. The product can be a naked product or a product pre-loaded onto a tray. A tube of plastic wrap is continuously fed through a bag/package forming, filling and sealing apparatus. The film and the product are joined, for example the product is deposited on the film or the film is wrapped around the product. In some examples, the naked product is fed through an infeed belt. A tube is created around the product by sealing opposite longitudinal edges of the film. Alternatively, the product is placed in the tube and a leading edge of the packaging is sealed. Then the tube is sealed at the trailing edge (at the upstream end) of the package and is severed from the continuously moving tube of packaging.
The tube can be provided as a tube, or be formed from two films or webs sealed longitudinally at two longitudinal edges, or from a single film that is folded over and sealed along its longitudinal edges.
Sealing bars can be used to seal the package, wherein a lower bar and an upper bar are moved with respect to one another in order to contact each other, squeezing the packaging material in between and providing one or more seals. The sealing bars typically also form an adjacent seal, which comprises the opposite end of the next following package, thereby providing one semi-sealed (e.g. having an open end) and one sealed package during a single packaging process step.
The seals are typically transversally extending regions of packaging material that have been processed to provide a seal between the inside of the packaging and the environment. In some cases it is desirable to provide packaging that can easily be opened by a user prior to use of the packaged product. To this aim, the seal on one end of the packaged product can be provided with an incision or pre-cut section, which provides a pre-defined rupture zone, ensuring controlled rupture of the packaging film upon manual interaction of a user, thereby facilitating easy opening of the packaging and removal of the product contained therein.
The position of the pre-defined rupture zone can be adjusted depending on the product to be packaged, the film used, further use of the product when opened, and a number of other factors. For example, the pre-defined rupture zone can be positioned substantially in the middle of a transversal seal or near to one of the edges of the package.
The seals and rupture zones are created by a set of sealing bars that includes a blade for cutting the packaging between the seals of two subsequently packaged products and a knife for creating the pre-defined rupture zone or pre-cut section. The pre-cut section is designed to leave the seal intact while providing a pre-determined breaking point at which the packaging film is designed to rupture in a controlled manner upon manual interaction.
A packaging apparatus is typically used for numerous different products with respect to the type of product, size, weight, composition, etc. The problem is to provide different kinds of packages with respective rupture zones either substantially in the middle of a seal or with an offset towards one of the edges of the product. In some cases, the use of the product requires breaking the seal while leaving the packaging substantially intact for further processing (e.g., heating). In other cases, the use of the product requires breaking the seal and rupturing the entire package in order to expose the entire contents of the package.
The manner of breaking the seal at the pre-defined rupture zone depends on a number of factors, for example, the type and composition of the packaging film, the packaged product, etc. An additional factor includes the size of the pre-defined rupture zone. Providing a larger or smaller pre-defined rupture zone influences the rupturing process. Another additional factor includes the amount of air trapped in the packaging material near and around the pre-defined rupture zone. The pre-defined rupture zone can include pockets of air, separately and/or substantially sealed from the environment in order to provide a gripping area. The amount of air and, hence, the shape and composition of the gripping area, influences the rupturing process.
Gas can be trapped in the package in the space between the product and the film after sealing both ends. It is sometimes desirable to deflate the package so as to reduce the package volume. Additionally, evacuation of the gas from the package can improve packaging appearance after heat shrinking and can also reduce the possibility of deterioration of the product due to exposure to oxygen or other gas. For example, some foods such as cheese can oxidize or mold over a period of time if a suitable atmosphere is not contained within the package.
WO 2013/055848 describes a packaging article including a heat-shrinkable multilayer film having a heat seal extending down a length of the packaging article along longitudinal edges of the film, a heat seal extending across a width of the packaging article and providing a bottom of the internal volume within the packaging article, and a heat seal extending across the width of the packaging article and providing a top of the internal volume. The packaging article also comprises a skirt between the heat seal across the width of the article and the bottom edge of the article. The skirt has tear initiators, which are cuts through the skirt, with each of the tear initiators having an inward end and an outward end. The inward ends are closer to both the first two heat seals than are the outward ends, and the outward ends are closer to the bottom edge than are the inward ends. The tear initiators are positioned relative to the first heat seal so that a superimposed straight line extending through the inward and outward ends of each tear initiator intersects a superimposed straight line extending through the ends of the first heat seal at a lesser included angle of from 25 degrees to 55 degrees, with the inward end of each the first and second tear initiators terminating at a location which is from 3 to 30 millimeters from the first heat seal and 3 to 50 millimeters from the second heat seal. The heat-shrinkable film exhibits an Elmendorf tear strength of from 0.7N to 2N after shrinking.
U.S. Pat. No. 5,673,534 describes a re-closable bag that includes a detachable re-closure tie having a tail portion formed by a series of spaced elongated seals and a closed loop. Apparatus for forming the re-closure tie with a bag includes first and second sealing jaws with external and internal grippers for holding web material. The first sealing jaw carries cutting and perforating knives and a cooling block that directs cooling air onto the knives to prevent the knife temperature from rising to the melting temperature of the web material. Each sealing jaw contains a heating block with complementary sealing surfaces for forming various seals including the seals that form the tail portion of the re-closure tie. U.S. Pat. No. 5,284,002 describes a storage bag and a method and apparatus for forming the storage bag. The storage bag contains a re-closure tie formed as an integral marginal portion of the bag beyond an edge of the bag. The marginal portion includes overlying layers of bag material that form an elongated structure along an axis with first and second ends. A fused closure is formed in the marginal portion parallel to the axis and over a portion of the marginal portion spaced from one end thereof. This structure defines a tail and open loop that wrap around an opened bag thereby to close the bag in a positive fashion. U.S. Pat. No. 5,169,696 describes a transversely tearable film and pouches made therefrom. The transversely tearable laminate comprises a machine direction oriented linear low density polyethylene film adhesively laminated on at least one side to a sealant film, the sealant film having an Elmendorf tear in the machine direction of at least about 2 g per micron. None of these documents describe how re-closure ties or tearable portions of film can be modified in order to adapt to different applications.
U.S. Pat. No. 4,650,079 describes an easy-to-open synthetic resin bag, which includes a bag body constituted by a laminated film formed by laminating several layers of synthetic resin film, a tear string bonded to part of an inner surface of the bag body corresponding to the opening thereof, and a tab formed at an end of the tear string. Pulling the tear string by the tab enables one side surface of the bag to be torn open, thereby allowing the bag to be opened. Also disclosed is a bag manufacturing apparatus capable of automatically bonding the tear string to the part of the inner surface of the bag body corresponding to the opening thereof when the bag body is being formed by employing the laminated film of the above kind. The document does not describe how packaging material or tear strings are or can be configured for different applications.
U.S. Pat. No. 6,343,876 describes a packaging machine, in which below a laterally sealing mechanism a seal opening notch forming mechanism is arranged, below which a perforation slitter mechanism is disposed to form perforations in a center longitudinally sealed portion of left and right parallel package bags. Further blow the perforation slitter mechanism there is a cutting mechanism that cuts laterally sealed portions of vertically connected package bags and delivers separated package bags. WO0164516 describes a filling and packaging machine capable of sealing packaged substance such as liquid, powder, or viscous substance by sealing a package film on three or four longitudinal and lateral sides thereof, comprising a trimming mechanism having a trimming blade for cutting an ear parts forming cut wastes by the vertical seal parts of continuously fed package bags and a sucking mechanism having a sucking port for sucking to collect the ear parts forming the cut wastes provided on the downstream side of the trimming mechanism, whereby the cut wastes of the package bags can be excluded satisfactorily. U.S. Pat. No. 4,981,374 describes a machine for automatically filling plastic bags with liquid or particulate material, which moves a continuous web of such bags through a number of serially positioned work stations. The machine can be manually adjusted to handle bags of different width. An additional adjustment by means of stepper motors is also provided.
An aim of the present invention is to provide a packaging process in which the seal of a packaged product is provided with a pre-defined rupture zone wherein the size and/or position of the pre-defined rupture zone can be easily adjusted depending on a number of factors including product properties such as size, composition, and type. Another aim of the present invention is to provide a packaging apparatus adapted to form a seal having adjustable size and/or position of a pre-defined rupture zone. In particular it is a goal of the invention to provide a packaging apparatus capable of executing the packaging process of the invention. Furthermore, it is an aim of the invention to provide a device for cutting and sealing a film in the above packaging apparatus or process.